Calculating Electron-Transfer Coupling with Density Functional Theory: The Long-Range-Corrected Density Functionals.

Area of Science:

• Quantum Chemistry
• Computational Chemistry
• Materials Science

Background:

• Standard density functional theory (DFT) methods often fail for charge-transfer (CT) problems.
• Long-range-corrected (LC) DFT functionals improve CT state predictions by incorporating Hartree-Fock exchange at long ranges.

Purpose of the Study:

• To evaluate the performance of LC-DFT for calculating charge-transfer couplings.
• To develop a nonempirical approach for optimizing the range-separation parameter in LC-DFT.

Main Methods:

• Testing LC-DFT on charge-transfer (ET) couplings.
• Nonempirical optimization of the range-separation parameter by minimizing orbital energy differences with ionization potentials/electron affinities.
• Comparing LC-DFT results with coupled cluster (CC) and experimental Mulliken-Hush data.

Main Results:

• Optimized LC-DFT yields ET couplings comparable to coupled cluster methods.
• LC-DFT results show significant improvement over standard DFT when compared to experimental data.
• The BNL and LC-BLYP functionals provided superior results compared to LC-ωPBE and LC-ωPBE0.

Conclusions:

• LC-DFT is a suitable method for calculating ET couplings.
• The proposed nonempirical parameter optimization enhances the accuracy and applicability of LC-DFT for charge-transfer phenomena.